These loops depict the Supercell Composite Parameter (SCP) beneath radar-derived MESO/TVS alert markers (yellow dot=MESO alert, red triangle=TVS alert). The MESO/TVS plots are produced every 6 minutes but the plot displayed is only valid near the top of each hour.

The SCP is a multi-parameter index that includes effective SRH, muCAPE, and effective bulk shear. Each parameter is normalized to supercell "threshold" values. Effective SRH is divided by 50 m2/s2, muCAPE is divided by 1000 J/kg, and effective bulk shear is divided by 20 m/s in the shear range of 10-20 m/s. Effective bulk shear less than 10 m/s is set to zero, and effective bulk shear greater than 20 m/s is set to one.

This index is formulated as follows:

SCP = (muCAPE / 1000 J/kg) * (ESRH / 50 m2/s2) * (ESHEAR / 20 m/s)
(Note: 10m-500mb wind shear is used in place of effective shear for calculations of SCP from the Spring Program mesoscale models. Effective shear is used in the SFCOA SCP calculations.)

For example, an ESRH of 300 m2/s2, muCAPE of 3000 J/kg, and ESHEAR of 20 m/s results in a supercell composite index of 18. Only positive values of SCP are displayed.

Additional information can be found here. (Opens a PDF document.)